Pretty easy. A button has been added to the advanced reply/edit mode which will wrap the tags around selected text if you are too handicapped to type it out yourself.

Here is an example of the codes above (of course they are of videos I have personally made because I am selfish):

UPDATE: - If there is a higher quality version of the Youtube video stored on the site, it will now play as default when posted here. This also means Youtube videos can have stereo sound if available as well as fewer compression artifacts. Overall resolution is still the same.